Here's a simple recipe for Jajangmyeon (Serves 2-4):
1 1/2 cups pork butt, cut into cubes
1 cup onions, diced
1 cup potatoes (or zucchini), diced
5 Tbsp. black bean paste
2 tsp. sugar
2 cups water
2 Tbsp. cornstarch dissolved in 2-4 Tbsp. of cold water
400 g. noodles (you can used Pasta or Udon)
Fry the pork until golden brown, set aside. Cook the black bean paste on the same pan with the remaining oil. Add in onions and potatoes and stir fry for 2 minutes. Add the pork and water and boil until the potatoes are fork tender. Season with sugar. Lastly, add the thickener.
The paste already has some salt in it.